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May 3, 1949.
Filed Sept. 26, 194.4
. .
2 Sheets-Sheet 1
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. Ma)‘ 3,1949.
. Filed sepmze, 1944
2 Sheets-Sheet 2
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Patented May 3, 1949 '
Christian Meisser, Davos-Dorf, ‘Switzerland, as
signor to Sulzer Fréres, Société Anonyme, Win
terthur, Switzerland
Application September 26, 1944, Serial No. 555,790
In Switzerland December 11, 1948
;8 Claims. (Cl. 230-134)
may be obtained at the part of the rotor where
The invention relates to a centrifugal com
pressor for high stage-pressures and consists in
that the blades of the rotor extend diagonally
to the rotor axis and have at least two zones,
whereby in the inlet'zone the angle of inclina
tion of the backwardly bent blade-surface with
' respect to the peripheral direction increases
from the value required for freedom from shock
at ‘the inlet at normal load to a maximum value,
whilst in the outlet zone the blade-surfaces have
‘the diameter increases, forv instance by a con
stant pitch of the blades. In preferred forms
of execution of the centrifugal compressor ac
count is taken of these differences in construc
tion and service conditions by making the two‘
parts of the rotor separately and of different
materials. In consequence of the inlet part of the
rotor being of smaller diameter, it is subjected
10 to lower mechanical stresses than the outlet part.
a decreasing angle of inclination, whose cosine
at the point of outlet is greater than the ratio
of the relative velocity to twice the peripheral
velocity, so that the angle of inclination is again
The material used to make it can have less
strength and at the same time require a less
careful method of construction to be adopted
than for the outlet part, which is very highly
reduced from the maximum value to a value at 15 stressed in consequence of the high peripheral
speeds and is therefore preferably shaped, vat
which the absolute outlet velocity does not ex
ceed the velocity of sound to such an extent that
Mach sound waves can be formed.
strength and without any central bore. I Thus
the inlet part with its hub might be made of a
Advantages with regard to the flow through
the compressor, its construction and its work 20 casting, for instance of steel, light metal, or such
like. It would also be possible to ilnish the
ing, are obtainablewith a compressor according
blades of the inlet part together with the hub
to the invention. The increase in the angle of
as one pressed part, for instance from some kind I
inclination of the blades with respect to the
peripheral direction, from the inlet onwards in
of plastic material, such as‘v Bakelite, Press
Further’ the blades and. the hub of
the direction of ?ow, causes a retardation of the 25 spahn, etc.
the inlet party could each be made separately as
pressed parts and then ?tted together, for in
stance by welding or by means of suitable
zone of the rotor being mainly axial, the centri
grooves in the hub. The blades of the inlet part
fugal and Coriolis accelerations have no essen
tial in?uence. The medium flowing in this man 30 could be made together with the hub from one
piece of metal by adopting some suitable method
ner thoughthe second zone of therotor has, in _
of machining, for instance, by milling from the
consequence of its precompression, a higher spe
solid or from pre-shaped material.
ci?c gravity, so that an increase in the stage
Making the rotor of the compressor in two
pressure is made possible by guiding the ?ow
relative ?ow, accompanied by a rise in pressure.
In consequence of the direction of ?ow in this
from a smaller to a greater diameter under the '
action of greater centrifugal and Coriolis accel- ' 3.5
In the second rotor-zone with backwardly
bent blades, i.‘ e. the zone at the outletv end,'the
vparts has’ further the advantage that one and
the same outlet part of the rotor can be adopted
for ‘different working conditions by ?tting it with
interchangeable inlet parts, since only the lat
ter have to be suited within wide limits to
eral direction decreases up to the blade-outlet,
changing working conditions. .The number of
blades'of the inlet part or of the-several inlet
whereby, in addition. to the desired reduction of v
parts may be the same as the number in the
angle of inclination with respect to the periph
main rotor, or the number may be lessor greater.
When the number of blades on the inlet part
tion of the ?ow occurs, which prevents any ex
cessive loading of the blades or any deviation ' 45 and on the outlet part of the rotor is the same,
they may be arranged directly in line with eachv
of the flow from them caused by such loading.
The transfer of energy from the blades to the
other or displacedwithrespect to each-other.
medium handled can therefore take place with
If the blades‘ on the outlet part of the rotor and
the absolute outlet velocity, a relative accelerae
- on the one or more inlet parts are displaced with
The conditions of ?ow are different in the two
50 respect ‘to each other, the angles of both to the
zones of the rotor, and in consequence of the
peripheral direction at theregion of displace
small diameter of the rotor at the inlet end and
ment may be the same or different. Theform
outdisturbance arising.
the increasing diameter towards the outlet end
the two zones are subjected to greatly differing
of the blades may be aerofoil. The centrifugal
compressor may be constructed in such va way
centrifugal stresses. vThe diminishing angle of
55 that it is possible quickly to change the inlet
inclination of the blades, in the direction of ?ow
part, or the several inlet parts, for parts with'.
the peripheral direction decreases to the out
let angle 48:. The cosine or the angle p; is great
a dl?erent inlet-characteristic.
Fixed or adjustable guide blades may be are
ranged in front of the inlet parts. If these‘
guide blades are ?xed, it would be possible to
er than the ratio of the relative velocity to twice
the-peripheral velocity. With theworkin'g conr
ditions occurring in/practice the angle vwill
constructthem as supporting ribs connected to
the inlet casing, for taking a rotor bearing.
In order ‘that the medium handled may be
guided to the inlet part in a manner suitable to
changeable working conditions, and in order to 10
ensure high emciencies over a Very large serv
ice range, the guide blades may be constructed
so that they can be adjusted while the compres
amountto about 45°. ,_ The separation between
the zonesE and- F in Figs. 2 and 3 occurs ap
proximately along the line 3-3, at a point of
in?ection in the bending of the blades. Whilst
the blades of the inlet part have an increasing
pitch and an increasing cross-section of ?ow and
extend for the most part axially, the outlet part
can have blades of a constant pitch and extend
sor is at rest or while it is running. They may
in a pronounced radial direction and less pro
be movable about the rotor axis or have an axis 15 nounced axial direction,’ thus'causing the angle
of rotation cutting or crossing the rotor axis.
of inclination of the blade with respect to the
In addition to the guide blades, the blades on
peripheral direction to be reduced, as desired,
one or several inlet parts of the rotor might also
from the maximum‘ value p: to the outlet an
be arranged adjustable in the manner mentioned.
gle B3. _
In. the case of blades automatically adjustable 20' The centrifugal compressor according to Fig.
duringservice, this could be effected by adopt
ing electrical,” hydraulic, pneumatic or mechani
- 4 has a rotor part 9 at the outlet end which is
machined, along with the blades ll'L'out or the.
solid. The material used is preferably a light
metal alloy of great tensile strength, for instance,
lDuralumin, Elektron, and such like, in order to
cal means and dependent on one or several serv
icefactors, for instance the pressure of the me
dium handled.
In so far as the blades of the inlet part of
the rotor and of the guide apparatus are ar
be able towithstand the centrifugal stresses oc
' curring at peripheral velocities of 400 m./sec.
ranged to be adjustable, their adjusting mecha
nisms could be coupled together in accordance;
and higher. In order to prevent any bending
stresses in the cross-section of the blades [0 nor-'
with some law of motion which ensures a high 30 mal to the rotor axis, they extend radially to that
‘ overall efficiency. the combined adjustment being
:axis. By screwing backwards lnthe axial direc
eifected either automatically or by hand.
tion they make an angle with respect to the pe
Examples of executions in accordance with the I
subject matter of the invention are represented
on the accompanying drawings, where
Fig. I shows in longitudinal section a centrif
, ugal compressor whose rotor is in one piece, and
Fig. 2 a side view of the rotor, whilst
ripheral direction whose cosine is greater than
the ratio of the relative velocity to twice the pe
ripheral velocity. In this way, in spite of the
peripheral velocity of the rotor being higher than
the velocity of sound in the medium handled, the,
absolute outlet velocity of the medium can be
Fig. 3 is the development of a blade along the
brought below the velocity of sound in it and pre
line I—-I in Fig. 2.
40 vent the occurrence of. Mach waves. In .order
Fig. 4 illustrates a longitudinal section of a
that the rotor part 9 may be able to withstand
centrifugal compressor with the rotor in two‘
the high centrifugal stresses, it is constructed, at
least approximately, as a disc of uniform strength.
In order to prevent any dangerous edge stresses
Figs. 5 and 6 show suitable blade arrangements
~ of centrifugal compressors consisting of an inlet 45 this rotor part 9 is made without a central bore
part and an outlet part, developed along the line
11-11 of Fig. 4.
Fig. 7 shows in longitudinal section a centrif-v
ugal compressor whose rotor is formed of four
parts, and
and ?anged to the shaft 3, and it is also provided
at the inlet end with a centered annular groove
ll into which is inserted the central continua
tion of the hub i2 of the inlet part provided with
'50 the inlet blades l3 and secured to the rotor part
Fig. 8 a blade arrangement for. that compres
sor developed along the line I1I—III in Fig. 7.
The centrifugal compressor according to Figs.
1 and 2 has a rotor l, which is provided with
backwardly bent blades 2 extending diagonally to
the rotor axis and arranged in the form of a
screw. The rotor I, which has no central’ bore,
is ?anged to the shaft 3 and‘ carried overhung
of aerofoil section and arranged according to the
in one or more bearings 4. At the inlet end the
- blade drawings in Figs. 5 and 6. The two rotor
9 to prevent one of them turning with respect
to the other. By means of the axial bolt ll
?xed in the hub'of the rotor part 9 and of the
covering hood 15 arranged on this bolt, the in
let part l2, i3 is secured against being axially
displaced with respect to the rotor part 9.
The inlet blades l3, Fig. 4, are preferably made
covering hood 5 is connected to the rotor I. The 60 parts 9 and I2, supported overhung at the inlet
rotor I is surrounded by the casing 6 which leads
end, are surrounded by the‘ casing 6 which leads.
through a diffusor 1 into the outlet spiral 8.
into the diifusor 1 and the outlet spiral 8. The
The blades 2, arranged diagonally extended on
shape and arrangement of the blades correspond
the rotor body I and in ‘the form of a screw (Figs.
essentially to those shown in Figs. 1, 2 and 3.
1, 2 and 3), have two zones E and F (Figs. 2 65
The centrifugal compressor shown in Fig. 7 has
and 3). At the beginning of the inlet zone E
a rotor part9 at the outlet end which is essenti
the blades 2 are inclined at the angle #1 to the
ally shaped similarly to-the outlet part shown in
peripheral direction u, as is obtained from the
Fig. 4. In the centered annular groove ll one
inlet triangle of velocities for given working con
inlet part I5 is inserted. This has‘ also a centered
"ditions'at normal loading for inlet free from. 70 annular groove IS, in which the middle inlet part
shock, and amounts for instance to 30°. In the
I‘! is held. In' the same manner the ?rst inlet
direction of ?ow indicated by the arrow A the,
part III is ?xed on the middle inlet ‘part. In the
angle increases up to a maximum value 52, and
rotor part 9 at the outlet side the axial bolt, I9 is
amounts for instance to 60“. In the outlet zone
?xed, whose free end has a plate 29' on which a
the angle which the blade surface makes with 75 bearing pin 2| is ?tted. Through the bolt l9 the
plate 20 keeps the inlet parts l5, l1‘ and I8 from
being displaced axially. The bearing pin ‘M is
2. A centrifugal compressor according to claim
1 in which the inlet and outlet parts of the rotor
are separable members each carrying its own
supported within a covering hood 22, held by a
blading detachably assembled into a unitary rotor
plurality of bracing ribs 23 which are connected
to the casing 6.
3. A centrifugal compressor according to claim
The blading 24 of the inlet parts l5, l1 and I8,
2 in which the separable rotor members are con
Fig. 7, may be arranged in the form of a grid,
structed of different materials.
displaced with respect to each other, as shown in
4. A centrifugal compressor according to claim
the blade drawings in Fig. 8. They may, how
ever, also pass to the blades Ill of the rotor part 10 3 in which the outlet rotor member is formed at
least approximately as a disc of uniform tensile
9 in uniform progression over all three inlet parts._
strength and without any central bore.
If the blades of the inlet part and of the guide
5. A centrifugal compressor according to claim
apparatus are arranged to be adjustable instead
4 in whichthe inlet rotor member consists of a
of being ?xed, the two adjusting mechanisms can
be coupled to each other according to a law of 15 relatively light blade carrying annulus assembled
to the outlet member by clamping through its
motion ensuring a high overall efficiency, and this
central bore.
combined adjustment may be effected automati
6.’ A centrifugal compressor according to claim
cally in accordance with one or more service fac
1 in which the inlet'and outlet parts of the rotor
tors or by hand. In this manner a high overall
e?iciency can be obtained over a wide range of 20 are separable members each carrying its own
blading detachably assembled into a unitary rotor
structure and in which the blades in the inlet
- I claim:
zone are offset. on the blades of the outlet zone.
1. A centrifugal compressor suitable for high
7. A compressor according to claim 6 in which
peripheral speeds, comprising a rotor, to be driven
at a peripheral speed not less than 300 meters per 25 the offset of the blades in the inlet zone from the
blades of the outlet zone can be adjusted by rela
second, with a plurality of blades extending from
tive rotation of their respective rotor members
the inlet part on a small diameter to the outlet
about the rotor axis.
part on a greater diameter, the latter part being
8. A compressor according to claim 1 in which
spaced axially from the former, the blades being
bent backwards throughout their length and hav 30 the blades in the inlet zone have an airfoil form.
ing at least two zones‘, one, an inlet zone in which
the angle of inclination of the backwardly bent
blade surfaces with respect to the peripheral
The following references are of record in the
direction increases from the relatively small angle‘
required for freedom from shock at the inlet at 35 ?le of this patent:
normal load to the maximum value attained from
inlet to outlet, and the other, an outlet zone in
which the angle of inclination of the backwardly
bent blade surfaces with respect to the peripheral
direction decreases from the maximum value at 40
tained from inlet to outlet to an angle at the
outlet whose cosine is greater than the ratio of
the relative velocity to twice the peripheral
DeVallat __________ __ Oct. 29,
Moss ______________ __ Oct. 7,
Criqui _____________ __ June 1,
Rees ______________ __ July 29,
Huber ______________ __ Feb. 6,
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